Flexible AC Transmission System (FACTS) devices play a vital role in improving the static as well as dynamic performance of the power system. They serve to make the otherwise rigid, conventional AC systems flexible ones as they make it possible to adjust the bus voltage magnitudes, phase angles and line impedances at faster rates in the required directions which will result in the improvement of stability and bus voltage profiles and reduction of real and reactive power losses. In order to tap maximum benefits out of their installation, the location and ratings of the FACTS devices are to be chosen optimally. In this paper a PSO based technique has been presented for solving the problem of device placement and an objective function comprising the weighted sum of the indicators of line loadings, bus voltage deviations and device cost functions has been formulated . The objective function is solved through the application of PSO technique and testing has been done using IEEE 14, 30 and 57 bus systems Keywords: FACTS devices, Thyristor Controlled Series Capacitor (TCSC), Static Var Compensator (SVC), Particle Swarm Optimization (PSO), Security enhancement.